Water-reducible coating composition

ABSTRACT

Coating compositions comprise a clear, homogeneous binder mixture of polyether or polyester polymer, an amine-formaldehyde condensate resin, and an organic solvent; the mixture being miscible with water to application viscosity. The coating composition typically contains suspended solid particulates, including pigments and metal flakes.

The present invention is directed to coating compositions which maycontain no water but which are reducible by water at the site ofapplication.

BACKGROUND OF THE INVENTION

Due to increasing environmental concerns there exists a need forcoatings with low solvent emissions. A growing number of states areplacing restrictions on the relative amounts of emitted solventspermitted for various types of coating applications. A VOC (volatileorganic content) of less than 2.0 pounds per gallon of product, asapplied, is desirable to meet the most demanding restrictions forsolvent-containing coatings. It has proven very difficult to apply asolvent-containing coating at VOC levels of 2.0 pounds per gallon orless and still achieve acceptable appearance in a decorative coating.This is especially true of polychromatic coatings, such as automotivebody finishes.

Water-based coatings can satisfy most VOC requirements. However,water-based coatings are unsuitable for certain purposes. In particular,water-based coatings cannot be used to supply a stable coatingcontaining a water-reactive metal, such as aluminum.

Water-reducible, solvent-containing coatings have been proposed having abinder system comprising an acrylic polymer having amine-neutralizedcarboxyl groups plus an amine-formaldehyde resin cross-linking agent.Such compositions are described, for example, in U.S. Pat. No.4,530,958, the teachings of which are incorporated herein by reference.Although such compositions have worked well for many coatingapplications, high viscosities of such compositions have made itdifficult to apply these compositions at high solids levels. Polymersachieving water solubility through amine neutralization of theircarboxyl groups yield relatively high viscosity in water compared totheir viscosity in organic solvents.

There exists a continued need for water-reducible coatings which providelow VOC's and which may be applied at high solids levels.

SUMMARY OF THE INVENTION

In accordance with the invention, a clear, homogeneous coating mixturecomprises: (A) from about 25 to about 95 wt. percent of a polymer whichis a polyether or polyester; (B) between about 2.5 and about 50 wt.percent of an amine-formaldehyde cross-linking resin; and (C) up toabout 50 wt percent of an organic solvent. The polymer,amine-formaldehyde resin and organic solvent are mutually compatible,forming a clear, homogeneous mixture when mixed in these proportions.The binder mixture is formulated so as to be sufficiently compatiblewith a volume of water equal to at least about one fifth the totalvolume of the coating binder mixture ((A)+(B)+(C)) and with sufficientadditional water to achieve a thinned viscosity of less than about 250cps so as to remain a clear, homogeneous mixture, whereby the coatingcomposition may be reduced with water at the site of application. Thepolymer is substantially non-ionic, having an acid number below about15. The polymer has terminal and/or pendant hydroxyl groups sufficientto provide a hydroxyl value of between about 100 and about 1000.

DETAILED DESCRIPTION OF CERTAIN PREFERRED EMBODIMENTS

Coating compositions in accordance with the invention have a binderwhich is a clear, homogeneous mixture of: (A) a generally non-ionichydroxyl group-containing polyether or polyester polymer; (B) anamine-formaldehyde resin; and, optionally, (C) an organic solvent Thepolymer, amine-formaldehyde resin and organic solvent are selected formutual compatibility so that, in combination, these components form aclear, homogeneous mixture The polymer, amine-formaldehyde resin, andorganic solvent are further selected so that the clear, homogeneousmixture of these components is sufficiently compatible with a volume ofwater equal to at least about one fifth the total volume of the coatingbinder mixture ((A)+(B)+(C)) and with sufficient additional water toachieve a thinned viscosity of less than about 250 cps (as measured on aBrookfield viscometer at 25° C.) so as to remain a clear, homogeneousmixture. This is not to say that each of these individual components,e.g., the polymer, is fully miscible in water, but only that each ofthese components be sufficiently miscible with or tolerant of water thatthese components in combination form a clear, homogeneous mixture whichremains a clear, homogeneous mixture when thinned with water.

The binder mixture's considerable compatibility with water makes coatingcompositions in accordance with the invention reducible with water. Thebinder mixture may, thereby, be mixed with concentrated levels of solidmaterials, such as pigments and metal particulates, which contribute tothe appearance of the coating and b®reduced with water at the point ofapplication providing a reduced coating composition which has arelatively low proportion of volatile organic solvents.

Water reducibility of coating compositions of the present invention isalso advantageous with respect to providing shelf-stable metalliccoatings. Metallic coatings generally contain metal flakes in additionto pigments. Many metal flakes are reactive with water; this isparticularly true of commonly used aluminum flakes. Coating compositionsin accordance with the present invention are formulated so that they maybe prepared, stored, and shipped without any water and then reduced withwater at the point of application. Aluminum and other water-reactivemetal flakes may be included in compositions according to this inventionwithout problems of fuming or instability. Absence of water from thestored and shipped compositions also avoids corrosion of containers anddegradation of pigments and resins, e.g., by hydrolysis anddeesterification. Coating compositions in accordance with the inventionhave the dual advantages of being water-free until used while beingwater-reducible to minimize solvent emissions at the point ofapplication.

There are a number of advantages to shipping and storing compositionsaccording to this invention without the inclusion of any water. However,the invention is intended to cover binder mixtures and coatingcompositions which are pre-thinned with water.

The solids of the binder mixture comprise the polymer (A) and theamine-formaldehyde resin (B). The polymer has functional groups.Particularly hydroxyl groups, by which the polymer may be cress-linked.The amine-formaldehyde resin serves as a cross-linker for the polymer,whereby, when the coating composition is applied to a surface the solidsof the binder mixture cure into a cross-linked network. The polymer (A)comprises between about 50 and about 95 wt. percent of the bindermixture solids (polymer plus amine-formaldehyde resin); theamine-formaldehyde resin (B) comprises between about 5 and about 50 wt.percent of the binder mixture solids. Together these binder mixturesolids comprise from about 50 to 100 wt. percent of the binder mixture.

If the polymer (A) and the amine-formaldehyde resin (B), together,provide a clear, homogeneous mixture which is of sufficiently lowviscosity, organic solvent (C) is not required. However, an organicsolvent may be necessary to provide a clear, homogeneous mixture of thepolymer and the amine-formaldehyde resin. Also, organic solventsgenerally tend to reduce the viscosity of the binder mixture. For thepurpose of the invention, it is preferred that the binder mixture have aviscosity, as measured on a Brookfield viscometer at 25° C., of 20,000cps or less, and more Preferably, of 10,000 cps or less.

The polymer in accordance with the present invention is selected forwater tolerance. It is preferred that the polymer be completely solublewith water; however, it is sufficient that the polymer in the presenceof the amine-formaldehyde resin and any organic solvent be sufficientlycompatible with a volume of water equal to at least about one fifth thetotal volume of the coating binder mixture ((A)+(B)+(C)) and withsufficient additional water to achieve a thinned viscosity of less thanabout 250 cps so as to remain a clear, homogeneous mixture, i.e.,without phase separation. The polymer is also selected for relativelylow viscosity, whereby the viscosities of the binder mixture set forthabove may be achieved. Consistent with low viscosities, polymers mostuseful for the binder mixtures have molecular weights (number average)of less than about 2000. Very low. e.g., less than about 300, molecularweight polymers may have a vapor pressure that is sufficiently high toresult in fuming problems in certain applications. It is preferred,therefore, that polymers used in the binder mixture have molecularweights (number average) above about 500. High molecular weight polymerstend to significantly increase the viscosity of the binder mixture andare, therefore, undesirable for many coating applications, particularlywhere the coating composition is to be applied by a spray form Ofcourse, a small portion of the polymer molecules may be outside themolecular weight ranges without causing significant problems withrespect to either fuming or high viscosity.

Polymers in accordance with the invention have substantial hydroxylfunctionality, polymers having hydroxyl values in about the 100 to 1000range being used. Preferably, the hydroxyl value of the polymer is inthe range of about 100 to about 600, a hydroxyl value of about 200 beingconsidered optimal at the present time. Hydroxyl functionality on thepolymer may be terminal and/or pendant to the polymer chain. Preferably,the polymer has terminal hydroxyl functionality; however, polymers withonly pendant hydroxyl functionality are useful, providing the polymer issufficiently tolerant of or miscible with water. If a mixture ofpolymers is used, the hydroxyl value of the polymer mixture is in theabove-recited range.

Polymers useful for the binder solution are generally non-ionic, but mayhave a small degree of acidic, i.e., carboxyl, functionality. Consistentwith good water solubility, the polymer (or mixture of polymers) shouldhave acid numbers of below about 15. Some acid functionality, however,may promote adhesion to certain surfaces. Carboxyl functionality may beprovided to an hydroxyl group-containing polymer, for example, byesterification with a dicarboxylic acid or its anhydride. These types ofpolymers are distinguished from acrylic polymers used in prior artcompositions which are partially or fully neutralized by amines polymersused in the binder solutions of the present invention are sufficientlylater compatible without any amine neutralization. The substantiallynon-ionic character of the polymer helps to ensure that the viscosity ofthe coating compositions is lowered, rather than raised, by the additionof water at the point of application. This is in contrast tocompositions based upon amine-neutralized polyacrylates which tend tothicken or gel in the presence of water.

Types of polymers useful in accordance with the invention includepolyhydroxy polyethers, polyhydroxy polyesters and mixtures thereof.Polyhydroxy Polyether polymers (functionality of 2 or more) result fromthe reaction of organic oxides (typically ethylene oxide, propyleneoxide. butylene oxide, etc. or mixtures thereof) with polyfunctionalsubstances such as water, ethylene glycol, propylene glycol, neopentylglycol, butylene glycol, 1,4-butanediol, hexylene glycol,1,6-hexanediol, the polyglycols such as diethylene glycol or triethyleneglycol, etc., the triols such as glycerine, trimethylol ethane,trimethylol propane, etc. and other higher functional alcohols such aspentaerythritol, sorbitol, mannitol, and the like. Polyhydroxy polyesterpolymers (functionality of 2 or more) result from the reaction ofpolycarboxylic acids or anhydrides (typically isophthalic acid, phthalicacid or anhydride, maleic acid or anhydride, fumaric acid, sebacic acid,azelaic acid, adipic acid, trimellitic acid or anhydride, etc.) withpolyhydroxy substances such as ethylene glycol, propylene glycol,neopentyl glycol, butylene glycol, 1,4-butanediol, hexylene glycol,1,6-hexanediol, the polyglycols such as diethylene glycol or triethyleneglycol, etc., the triols such as glycerine, trimetylol ethane,trimethylol propane, etc. and other higher functional alcohols such aspentaerythritol, sorbitol, mannitol, and the like.

Types of amine-formaldehyde resins useful in accordance with the presentinvention include urea-formaldehyde resins, melamine-formaldehyderesins, and mixtures thereof. Melamine-formaldehyde resins are generallypreferred to urea-formaldehyde resins from the standpoint of providingthe coating composition with good weatherability. Useful resinsaccording to the invention may include urea and/or a wide variety ofmelamines, including, but not limited to, di-, tri-, tetra-, penta-. andhexamethylol melamine, alkoxy (C₁₋₅) methyl melamine, melamine having amethylol group and alkoxy group (C₁₋₅), and urea-melaminecopolycondensate. A preferred resin is hexamethoxymethyl melamine.

Solvents are selected for enhancing miscibility of the binder solutioncomponents with each other and with water and also for the purpose oflowering viscosity. Suitable solvents include but are not limited tomethanol, ethanol, propanol, isopropanol, ethylene glycol-monomethylether, ethylene glycol-monoethyl ether, ethylene glycol monoisopropylether, ethylene glycol monobutyl ether, diethylene glycol monomethylether, diethylene glycol monoethyl ether, diethylene glycol monopropylether, diethylene glycol monobutyl ether, acetone, etc.

In addition to the binder mixture, coating compositions in accordancewith the present invention typically contain solid materials, such aspigments and metallic flakes. Types of useful metallic flakes include,but are not limited to, aluminum, copper, brass, micaceous iron oxide,bronze, and stainless steel. An important aspect of the invention isthat the coating compositions may be entirely free of water untilreduced at the site of application. The absence of water substantiallyenhances the stability of coating compositions containing water-reactivemetal flakes. The absence of water also avoids water degradation ofother solid pigment materials. Solid materials, including pigmentsand/or metallic flakes, may be suspended in the binder solution up to anequal amount by weight relative to the weight of the binder solids,i.e., the polymer plus the amine-formaldehyde resin.

In addition to the binder mixture and solid materials, coatingcompositions in accordance with the invention may contain minor amountsof additional components which are conventional in the art, such as slipagents, lubricants, UV absorbers, wetting agents, dispersing agents,anti-settling agents, thixotropic agents, inhibiters, catalysts, etc.

As one method of forming coating compositions in accordance with theinvention, the polymer(s), amine-formaldehyde resin(s) and organicsolvent(s) are mixed together to form a clear mixture. Then solidparticulates and other additives are added and mixed together to form asuspension.

Water is generally not added until at or close to the time ofapplication to a substrate surface. The amount of water required willdepend upon the unthinned viscosity of a specific coating compositionand the viscosity appropriate for applying the coating composition. Forspray application it is desirable to have a thinned viscosity of lessthan about 250 cps. Typically, the volume of water added is betweenabout one-fifth to twice the volume of the coating composition. Thewater may be added by batch mixing, or an intermix system employingeither static or mechanical intermixing.

To achieve rapid curing of the coating composition once applied to asurface, an acidic curing catalyst is generally used. To avoid prematurecuring, the curing catalyst is generally added at the site ofapplication, e.g., by prior mixture with the water. Blocked acidiccuring catalysts might be incorporated in the coating composition;however, to ensure against premature curing, it is preferred to add anycuring catalyst at the site of application. Suitable acidic curingagents include but are not limited to paratoluenesulfonic acid, maleicacid oxalic acid, fumaric acid, various substituted sulfonic acids,various substituted phosphoric acids, etc.

Coating compositions according to the present invention may be appliedby any conventional manner. Generally, it is contemplated that thecoating compositions will be applied by a spray method. Afterapplication, curing is promoted by elevated temperatures, e.g., bybaking at temperatures of about 80° C. to about 120° C. or higher.

The coating provided by the composition may be used alone, particularlyfor interior applications, e.g., interior automotive parts. Wheregreater weatherability is desired, e.g., for exterior automotive parts,a clear top coat may be applied over the coat formed from the coatingcompositions. Examples of automotive approved top coats are PittsburgTopcoat UCC-2000 and Bee Chemical Topcoat Q66291.

Compositions according to the invention are applicable to a variety ofsubstrate surfaces such as bare steel, primed metal and a variety ofpolymeric surfaces tolerant to baking temperatures such as TPU(Thermoplastic Urethane) and RIM (Reaction Injection Molded Urethane).

The invention will now be described in greater detail by way of specificexamples;

EXAMPLE 1

A composition was prepared consisting of the following componentsexpressed as parts by weight: 65.0 parts Olin Chemical PPC-T1000,polyether polyol (a triol with theoretical MW=1000 and theoretical OHvalue=168); 35.0 parts American Cyanamid Cymel 303,melamine-formaldehyde resin; 0.5 parts Dow Paint Additive #57; 20.0parts isopropyl alcohol; 20.0 parts Silberline 5245AR, aluminum paste.After simple stirring this yielded 140.5 parts of a homogenous "silver"paint.

EXAMPLE 2

A paint thinner was prepared consisting of the following componentsexpressed as parts by weight: 0.5 parts paratoluenesulfonic aciddissolved in 99.5 parts water.

EXAMPLE 3

140.5 parts of the paint prepared in EXAMPLE 1 were thinned with 100.0parts of the thinner prepared in EXAMPLE 2 and applied by air-atomizedspray at about 50 psig to a standard automotive test panel (Bonderite 40steel primed with "E-Coat" electrodepositon primer). After baking for 30minutes at 250° F. the paint was found to cure and have "SCOTCH-TAPE"adhesion over a cross-hatched area.

EXAMPLE 4

A composition was prepared consisting of the following componentsexpressed as parts by weight: 65.0 parts Olin Chemical PPC-T1000,polyether polyol (a triol with theoretical MW=1000 and theoretical OHvalue=168); 35.0 parts American Cyanamid Cymel 303,melamine-formaldehyde resin; 0.5 parts Dow Paint Additive #57; 20.0parts isopropyl alcohol; 1.5 parts General Aniline & Film Gafac RE877, awetting additive; 80.0 parts DuPont R960, titanium dioxide pigment. Thiscomposition was dispersed using a sand-mill to yield 202.0 parts of ahomogeneous "white" paint.

EXAMPLE 5

A paint thinner was prepared consisting of the following oomponentsexpressed as parts by weight: 0.5 parts paratoluenesulfonic aciddissolved in 49.5 parts water.

EXAMPLE 6

202.0 parts of the paint prepared in EXAMPLE 4 were thinned with 50.0parts of the thinner prepared in EXAMPLE 5 and applied by air-atomizedspray at about 50 psig to a standard automotive test panel (Bonderite 40steel primed with "E-Coat" electrodeposition Primer). After baking for30 minutes at 250° F. the paint was found to cure and have "SCOTCH-TAPE"adhesion over a cross-hatched area.

EXAMPLE 7

A composition was prepared consisting of the following componentsexpressed as parts by weight: 65.0 parts Union Carbide PPG-425,polyether polyol (a diol with theoretical MW=425 and theoretical OHvalue=264); 35.0 parts American Cyanamid Cymel 303,melamine-formaldehyde resin; 0.5 parts Dow Paint Additive #57; 20.0parts isopropyl alcohol; 20.0 parts Silberline 5245AR , aluminum paste.After simple stirring this yielded 140.5 parts of a homogeneous "silver"paint.

EXAMPLE 8

140.5 parts of the paint prepared in EXAMPLE 7 were thinned with 100.0parts of the thinner prepared in EXAMPLE 2 and applied by air-atomizedspray at about 50 psig to a standard automotive test panel (Bonderite 40steel primed With "E-Coat" electrodepositon primer). After baking for 30minutes at 250° F. the paint was found to cure and have "SCOTCH-TAPE"adhesion over a cross-hatched area.

EXAMPLE 9

A composition was prepared consisting of the following componentsexpressed as parts by weight: 65.0 parts Union Carbide PPG-425,polyether polyol (a diol with theoretical MW=425 and theoretical OHvalue=264); 35.0 parts American Cyanamid Cymel 303,melamine-formaldehyde resin; 0.5 parts Dow Paint Additive #57; 20.0parts isopropyl alcohol; 1.5 parts General Aniline & Film Gafac RE877, awetting additive; 80.0 parts DuPont R960, titanium dioxide pigment. Thiscomposition was dispersed using a sand-mill to yield 202.0 parts of ahomogeneous "white" paint.

EXAMPLE 10

202.0 parts of the paint prepared in EXAMPLE 9 were thinned with 50.0parts of the thinner prepared in EXAMPLE 5 and applied by air-atomizedspray at about 50 psig to a standard automotive test panel (Bonderite 40steel primed with "E-Coat" electrodepositon primer). After baking for 30minutes at 250° F. the paint was found to cure and have "SCOTCH-TAPE"adhesion over a cross-hatched area.

EXAMPLE 11

A composition was prepared consisting of the following componentsexpressed as parts by weight: 65.0 parts Union Carbide PPG-425,polyether polyol (a diol with theoretical MW=425 and theoretical OHvalue=264); 35.0 parts American Cyanamid Cymel 303,melamine-formaldehyde resin; 0.5 parts Dow Paint Additive #57; 20.0parts Silberline 5245AR, aluminum paste. After simple stirring thisyielded 120.5 parts of a homogeneous "silver" paint. Apparent viscositywas sufficiently low without necessity for addition of organic solvent.

EXAMPLE 12

120.5 parts of the paint prepared in EXAMPLE 11 were thinned with 100.0parts of the tinner prepared in EXAMPLE 2 and applied by air-atomizedspray at about 50 psig to a standard automotive test panel (Bonderite 40steel primed with "E-Coat" electrodepositon primer). After baking for 30minutes at 250° F. the paint was found to cure and have "SCOTCH-TAPE"adhesion over a cross-hatched area.

EXAMPLE 13

A composition was prepared consisting of the following componentsexpressed as parts by weight: 65.0 parts triethylene glycol (a diol withtheoretical MW=150 and theoretical OH value=748); 35.0 parts AmericanCyanamid Cymel 303, melamine-formaldehyde resin; 0.5 parts Dow PaintAdditive #57; 20.0 parts Silberline 5245AR, aluminum paste. After simplestirring this yielded 120.5 parts of a homogeneous "silver" paint

EXAMPLE 14

140.5 parts of the paint prepared in EXAMPLE 13 were thinned with 100.0parts of the thinner prepared in EXAMPLE 2 and applied by air-atomizedspray at about 50 psig to a standard automotive test Panel (Bonderite 40steel primed with "E-Coat" electrode position Primer). After baking for30 minutes at 250° F. the paint was found to cure and have "scotch-tape"adhesion over a cross-hatched area. Some fuming was observed duringbaking.

EXAMPLE 15

A composition was prepared consisting of the following componentsexpressed as parts by weight: 65.0 parts triethylene glycol (a diol withtheoretical MW=150 and theoretical OH value=748); 35.0 parts AmericanCyanamid Cymel 303, melamine-formaldehyde resin; 0.5 parts Dow PaintAdditive #57; 20.0 parts isopropyl alcohol; 1.5 parts General Aniline &Film Cafac RE877, a wetting additive; 80.0 parts DuPont R960, titaniumdioxide pigment. This composition was dispersed using a sand-mill toyield 202.0 parts of a homogeneous "white" paint.

EXAMPLE 16

202.0 parts of the paint prepared in EXAMPLE 15 were thinned with 50.0parts of the thinner prepared in EXAMPLE 5 and applied by air-atomizedspray at about: 50 psig to a standard automotive test panel (Bonderite40 steel primed with "E-Coat" electrodeposition primer). After bakingfor 30 minutes at 250° F. the paint was found to cure and have"SCOTCH-TAPE" adhesion over a cross-hatched area. Some fuming wasobserved during baking.

EXAMPLE 17

A composition was prepared consisting of the following componentsexpressed as parts by weight: 12.74 parts polyester resin prepared from2 moles PEG-300 per 1 mole adipic acid (theoretical MW=710 andtheoretical OH value=158); 27.82 parts Monsanto Resimene 745,melamine-formaldehyde resin; 25.52 parts PEC-400, polyethylene glycol;3.48 parts Hercules Klucel E, hydroxypropyl cellulose flow controladditive; 1.00 Parts Dow Chemical Paint additive #57; 16.98 partsisopropyl alcohol; 0.96 parts American Cyanamid Catalyst 4040; 12.00parts Silberline 5245 AR. aluminum paste. After simple stirring thisyielded 100.50 parts of a homogeneous "silver" paint.

100.50 parts of this silver paint was then thinned with 80.0 parts ofwater and applied by air-atomized spray at about 50 psig to a standardautomotive test panel (Bonderite 40 steel primed with "E-Coat"electrodeposition primer). After baking for 30 minutes at 250° F. thepaint was found to cure and have "SCOTCH-TAPE" adhesion over across-hatched area.

EXAMPLE 18

A composition was prepared consisting of the following componentsexpressed as parts by weight 17.39 parts of polyester resin preparedfrom 2 moles triethylene glycol per 1 mole adipic acid (theoreticalMW=410 and theoretical OH value=274); 13.91 parts American CyanamidCymel 303, melamine-formaldehyde resin; 34.78 parts PEG 400,polyethylene glycol; 3.48 parts Hercules Klucel E, hydroxypropylcellulose flow control additive; 1.00 parts Dow Chemical Paint Additive#57; 16.98 parts isopropyl alcohol, 1.92 parts of a "blocked" acidcatalyst (0.96 parts Catalyst 4040 plus 0.24 parts dimethylaminoethanolplus 0.96 parts isopropyl alcohol); 10.00 parts Silberline 5245 AR,aluminum paste. After simple stirring this yielded 99.46 parts of ahomogeneous "silver" paint.

99.46 parts of this silver paint was then thinned with 80.0 parts ofwater and applied by air-atomized spray at about 50 psig to a standardautomotive test panel (Bonderite 40 steel primed with "E-Coat"electrodeposition primer). After baking for 30 minutes at 250° F. thepaint was found to cure and have "scotch-tape" adhesion over across-hatched area.

EXAMPLE 19

A composition was prepared consisting of the following componentsexpressed as parts by weight: 65.0 parts Ruco Rucoflex LB-651, polyesterpolyol (a triol with theoretical MW=1000 and theoretical OH value=525);35.0 parts American Cyanamid Cymel 303, melamine-formaldehyde resin; 0.5parts Dow Paint Additive #57; 20.0 parts isopropyl alcohol; 20.0 partsSilberline 5245AR, aluminum paste. After simple stirring this yielded140.5 parts of a homogeneous "silver" paint.

EXAMPLE 20

140.5 parts of the paint prepared in EXAMPLE 19 were thinned with 100.0parts of the thinner prepared in EXAMPLE 2 and applied by air-atomizedspray at about 50 psig to a standard automotive test panel (Bonderite 40steel primed with "E-Coat" electrodepositon primer). After baking for 30minutes at 250° F. the paint was found to cure and have "SCOTCH-TAPE"adhesion over a cross-hatched area.

EXAMPLE 21

A composition was prepared consisting of the following componentsexpressed as parts by weight: 65.0 parts Ruco Rucoflex LB-651, polyesterpolyol (a triol with theoretical MW=1000 and theoretical OH value=525);35.0 parts American Cyanamid Cymel 303, melamine-formaldehyde resin; 0.5parts Dow Paint Additive #57; 20 0 parts isopropyl alcohol; 1.5 partsGeneral Aniline & Film Gafac RE877, a wetting additive; 80.0 partsDuPont R960, titanium dioxide pigment This composition was dispersedusing a sand-mill to yield 202.0 parts of a homogeneous "white" paintwith a viscosity of 900 cps as measured with a Brookfield viscosimeterusing a #3 spindle at 100 rpm.

EXAMPLE 22

202.0 parts of the paint prepared in EXAMPLE 21 were thinned with 50.0parts of the thinner prepared in EXAMPLE 5 and applied by air-atomizedspray at about 50 psig to a standard automotive test panel (Bonderite 40steel primed with "E-Coat" electrodeposition primer). After baking for30 minutes at 250° F. The paint was found to cure and have "scotch-tape"adhesion over a cross-hatched area. The viscosity of the thinned paintwas 180 cps as measured with a Brookfield Viscosimeter using a #2spindle at 100 rpm

EXAMPLE 23

A composition was prepared consisting of the following componentsexpressed as parts by weight: 80 0 parts Olin Chemical PPG-T1000,polyether polyol (a trio With theoretical MW=1000 and theoretical OHvalue=168); 20.0 parts American Cyanamid Cymel 303.melamine-formaldehyde resin; 0.5 parts Dow Paint Additive #57; 20.0parts isopropyl alcohol; 20.0 parts Silberline 5245AR, aluminum paste.After simple stirring this yielded 140.5 parts of a homogeneous "silver"paint.

EXAMPLE 24

140.5 parts of the paint prepared in EXAMPLE 23 were thinned with 100.0parts of the thinner prepared in EXAMPLE 2 and applied by air-atomizedspray at about 50 psig to a standard automotive test panel (Bonderite 40steel primed with "E-Coat" electrodepositon primer). After baking for 30minutes at 250° F. the paint was found to cure and have "SCOTCH-TAPE"adhesion over a cross-hatched area.

EXAMPLE 25

A composition was prepared consisting of the following componentsexpressed as parts by weight: 20.0 parts Olin Chemical PPG-T1000,polyether polyol (a triol with theoretical MW=1000 and theoretical OHvalue=168); 80.0 parts American Cyanamid Cymel 303 melamine-formaldehyderesin; 0.5 parts Dow Paint Additive #57; 20.0 parts isopropyl alcohol;20.0 parts Silberline 5245AR, aluminum Paste. After simple stirring thisyielded 140 5 parts of a homogeneous "silver" paint.

EXAMPLE 26

140.5 parts of the paint prepared in EXAMPLE 25 were thinned with 100.0parts of the thinner prepared in EXAMPLE 2 and applied by air-atomizedspray at about 50 psig to a standard automotive test panel (Bonderite 40steel primed with "E-Coat" electrodepositon primer). After baking for 30minutes at 250° F. the paint was found to cure and have "SCOTCH-TAPE"adhesion over a cross-hatched area.

EXAMPLE 27

A composition was prepared consisting of the following componentsexpressed as parts by weight: 65.0 parts Olin Chemical PPG-T1000,polyether polyol (a triol with theoretical MW=1000 and theoretical OHvalue=168); 35.0 parts American Cyanamid Cymel 303,melamine-formaldehyde resin; 0.5 parts Dow Paint Additive #57; 20.0parts dipropylene glycol monomethyl ether; 20.0 parts Silberline 5245AR,aluminum paste. After simple stirring this yielded 140.5 parts of ahomogeneous "silver" paint.

EXAMPLE 28

140.5 parts of the paint prepared in EXAMPLE 27 were thinned with 100.0parts of the thinner prepared in EXAMPLE 2 and applied by air-atomizedspray at about 50 psig to a standard automotive test panel (Bonderite 40steel primed with "E-Coat" electrodepositon primer). After baking for 30minutes at 250° F. the paint was found to cure and have "SCOTCH-TAPE"adhesion over a cross-hatched area.

EXAMPLE 29

A composition was prepared consisting of the following componentsexpressed as parts by weight: 65.0 parts Olin Chemical PPG-T1000,polyether polyol (a triol with theoretical MW=1000 and theoretical OHvalue=168); 35.0 parts Cargill Melamine 2387, melamine-formaldehyderesin; 0.5 parts Dow Paint Additive #57; 20.0 parts isopropyl alcohol;20.0 parts Silberline 5245AR, aluminum paste. After simple stirring thisyielded 140.5 parts of a homogeneous "silver" paint.

EXAMPLE 30

140.5 parts of the paint prepared in EXAMPLE 29 were thinned with 100.0parts of the thinner prepared in EXAMPLE 2 and applied by air-atomizedspray at about 50 psig to a standard automotive test panel (Bonderite 40steel primed with "E-Coat" electrodepositon primer). After baking for 30minutes at 250° F. the paint was found to cure and have "SCOTCH-TAPE"adhesion over a cross-hatched area.

EXAMPLE 31

A composition was prepared consisting of the following componentsexpressed as parts by weight: 65.0 parts Olin Chemical PPG-T1000,polyether polyol (a triol with theoretical MW=1000 and theoretical OHvalue=168); 35.0 parts American Cyanamid Beetle 80, urea-formaldehyderesin; 0.5 parts Dow Paint Additive #57; 20.0 parts isopropyl alcohol;20.0 parts Silberline 5245AR, aluminum paste. After simple stirring thisyielded 140.5 parts of a homogeneous "silver" paint.

EXAMPLE 32

140.5 parts of the paint prepared in EXAMPLE 31 were thinned with 100.0parts of the thinner prepared in EXAMPLE 2 MW =1000 and theoretical OHvalue =168); 35.0 parts American and applied by air-atomized spray atabout 50 psig to a standard automotive test panel (Bonderite 40 steelPrimed with "E-Coat" electrodepositon primer). After baking for 30minutes at 250° F. the paint was found to cure and have "SCOTCH-TAPE"adhesion over a cross-hatched area.

EXAMPLE 33

A composition was prepared consisting of the following componentsexpressed as parts by weight: 65.0 parts Olin Chemical PPG-T1000,polyether polyol (a triol with theoretical MW=1000 and theoretical OHvalue=168); 35.0 parts American Cyanamid Cymel 303,melamine-formaldehyde resin; 0.5 parts Dow Paint Additive #57; 20.0parts isopropyl alcohol; 20.0 parts Silberline 5245AR, aluminum paste;0.5 parts paratoluenesulfonic acid. After simple stirring this yielded141.0 parts of a homogeneous "silver" paint.

EXAMPLE 34

141.0 parts of the paint prepared in EXAMPLE 33 were thinned with 100.0parts of water and applied by air-atomized spray at about 50 psig to astandard automotive test panel (Bonderite 40 steel primed with "E-Coat"electrodepositon primer). After baking for 30 minutes at 250° F. thepaint was found to cure and have "SCOTCH-TAPE" adhesion over across-hatched area.

EXAMPLE 35

A composition was prepared consisting of the following componentsexpressed as parts by weight: 65.0 parts Olin Chemical PPC-T1000,polyether polyol (a triol with theoretical MW=1000 and theoretical OHvalue=168); 35.0 parts American Cyanamid Cymel 303,melamine-formaldehyde resin; 0.5 parts Dow Paint Additive #57; 20.0parts isopropyl alcohol; 20.0 parts Silberline 5245AR, aluminum paste;0.5 parts paratoluenesulfonic acid "blocked" with 0.27 partsdimethylaminoethanol. After simple stirring this yielded 141.27 parts ofa homogeneous "silver" paint.

EXAMPLE 36

141.27 parts of the paint prepared in EXAMPLE 33 were thinned with 100.0parts of water and applied by air-atomized spray at about 50 psig to astandard automotive test panel (Bonderite 40 steel primed with "E-Coat"electrodepositon primer). After baking for 30 minutes at 250° F. thepaint was found to cure and have "SCOTCH-TAPE" adhesion over across-hatched area.

EXAMPLE 37

140.5 parts of the paint prepared in EXAMPLE 1 were thinned with 100.0parts of the thinner prepared in EXAMPLE 2 and applied by air-atomizedspray at about 50 psig to three additional substrates: bare steel, TPU(Thermoplastic Urethane) and RIM (Reaction Injection Molded Urethane).After baking for 30 minutes at 250° F. the paint was found to cure andhave "SCOTCH-TAPE" adhesion over a cross-hatched area of each of thethree different substrates.

EXAMPLE 38

140.5 parts of the paint prepared in EXAMPLE 1 were thinned with 100.0parts of the thinner prepared in EXAMPLE 2 and applied by air-atomizedspray at about 50 psig to a standard automotive test panel (Bonderite 40steel primed with "E-Coat" electrodepositon primer). After force-dryingfor 3 minutes at 250° F. a clear "one Pack" automotive approved topcoatwas applied by spray. The topcoat was Pittsburg Topcoat UCC-2000 thinnedto 25 seconds on a #2 Zahn cup with a thinner consisting of a 50/50mixture of xylol and methyl n-Amyl ketone. After an additional bakingfor 30 minutes at 250° F. the combination of coatings was found to have"SCOTCH-TAPE" adhesion over a cross-hatched area. adhesion over across-hatched area.

EXAMPLE 39

140.5 parts of the paint prepared in EXAMPLE 1 were thinned with 100.0parts of the thinner prepared in EXAMPLE 2 and applied by air-atomizedspray at about 50 psig to a standard automotive test panel (Bonderite 40steel primed with "E-Coat" electrodepositon primer). After force-dryingfor 3 minutes at 250° F. a clear "two pack" Automotive approved topcoatwas applied by spray. The topcoat consisted of 88 parts by weight of BeeChemical Topcoat Q-66291 mixed with 12 parts by weight of Bee ChemicalCatalyst C-775. After an additional baking for 30 minutes at 250° F. thecombination of coatings was found to have "SCOTCH-TAPE" adhesion over across-hatched area. adhesion over a cross-hatched area.

While the invention has been described in terms of certain preferredembodiments, modifications obvious to one with ordinary skill in the artmay be made without departing from the scope of the present invention.

Various features of the invention are set forth in the following claims:

What is claimed is:
 1. A clear, homogeneous coating binder solutioncomprising:I. an organic component binder mixture comprising(A) betweenabout 25 and about 95 wt. percent of a polymer which is a polyether orhas both ether and ester linkages, said polymer having an acid numberbelow about 15 and an hydroxyl value in the range of between about 100to about 1000, (B) between about 2.5 and about 50 wt. percent of anamine-formaldehyde resin, and (C) up to about 50 wt. percent of anorganic solvent;said components (A), (B), and (C) being mutuallycompatible so as to form a clear, homogeneous organic component bindermixture in the absence of water; said organic component binder mixturebeing sufficiently compatible with a volume of water equal to at leastabout one fifth the total volume of said organic component bindermixture and with sufficient additional water to achieve a thinnedviscosity of less than about 250 cps so as to remain a clear homogeneoussolution, plus II. a volume of water equal to at least about one fifththe volume of said organic component binder mixture plus sufficientadditional water to achieve a thinned viscosity of less than about 250cps.
 2. A binder solution according to claim 1 which said organiccomponent binder mixture has a Brookfield viscosity at 25° C. of about20,000 cps or less.
 3. A binder solution according to claim 1 whereinsaid polymer is a polyether polyol derived from the groups consisting ofethylene oxide, propylene oxide and mixtures thereof.
 4. A bindersolution according to claim 1 wherein said polymer has both ether andester linkages and is derived from polyethylene glycol andpolyfunctional carboxylic acids.
 5. A binder solution according to claim4 wherein said polymer is derived from polyethylene glycol and adipicacid.
 6. A binder solution according to claim 1 wherein aidamine-formaldehyde resin is selected from the groups consisting ofmelamine-formaldehyde resins, urea-formaldehyde resins and mixturesthereof.
 7. A binder solution according to claim 1 wherein saidamine-formaldehyde resin is hexamethoxymethyl melamine.
 8. A bindersolution according to claim 1 wherein said organic solvent is selectedfrom the group consisting of methanol, ethanol, propanol, isopropanol,ethylene glycol-monomethyl ether, ethylene glycol-monoethyl ether,ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether,diethylene glycol monomethyl ether, diethylene glycol monoethyl ether,diethylene glycol monopropyl ether, diethylene glycol monobutyl ether,acetone and mixtures thereof.
 9. A binder solution according to claim 1wherein said polymer has an hydroxyl value of between about 100 andabout
 600. 10. A binder solution according to claim 1 plus a curecatalyst for said resin (B).
 11. A binder solution according to claim 10wherein said cure catalyst is provided separately from said organiccomponent binder mixture for admixture thereto at the site ofapplication.
 12. A coating composition comprising:(I) a clear,homogeneous organic component binder mixture comprising:(A) betweenabout 25 and about 95 wt. percent of a polymer which is a polyether orhas both ether and ester linkages, said polymer having an acid numberbelow about 15 and an hydroxyl value in the range of between about 100to about 1000, (B) between about 2.5 and about 50 wt. percent of anamine-formaldehyde resin, and (C) up to about 50 wt. percent of anorganic solvent;said components (A), (B), and (C) being sufficientlycompatible with a volume of water equal to at least about one fifth thetotal volume of said organic component binder mixture and withsufficient additional water to achieve a thinned viscosity of less thanabout 250 cps so as to remain a clear, homogeneous solution; and (II)suspended water-sensitive solid particulates at a weight level up toequal to that of the total weight of said polymer (A) plus said resin(B), said coating composition being free of water, yet reducible withwater.
 13. A composition according to claim 12 wherein said bindermixture has a Brookfield viscosity at 25° C. of about 20,000 cps orless.
 14. A composition according to claim 12 wherein said polymer is apolyether polyol derived from the group consisting of ethylene oxide,propylene oxide and mixtures thereof.
 15. A composition according toclaim 12 wherein said polymer has both ether and ester linkages and isderived from polyethylene glycol and polyfunctional carboxylic acids.16. A composition according to claim 15 wherein said polymer is derivedfrom polyethylene glycol and adipic acid.
 17. A composition according toclaim 12 wherein said amine-formaldehyde resin is selected from thegroup consisting of melamine-formaldehyde resins, urea-formaldehyderesins and mixtures thereof.
 18. A composition according to claim 12wherein said amine-formaldehyde resin is hexamethoymethyl melamine. 19.A composition according to claim 12 wherein said organic solvent isselected from the group consisting of methanol, ethanol, propanol,isopropanol, ethylene glycol-monomethyl ether, ethylene glycol-monoethylether, ethylene glycol monoisopropyl ether, ethylene glycol monobutylether, diethylene glycol monomethyl ether, diethylene glycol monoethylether, diethylene glycol monopropyl ether, diethylene glycol monobutylether, acetone and mixtures thereof.
 20. A composition according toclaim 12 wherein said polymer has an hydroxyl value of between about 100about
 600. 21. A composition according to claim 12 plus a cure catalystfor said resin (B).
 22. A composition according to claim 21 wherein saidcure catalyst is provided separately from said composition for admixturethereto at the site of application.
 23. A coating composition accordingto claim 12 wherein said water - sensitive solid particulates are metal.24. A coating composition according to claim 12 wherein said water -sensitive solid particulates are aluminum.